Vascular Plants of Williamson County Viburnum rufidulum − RUSTY BLACKHAW VIBURNUM, SOUTHERN BLACKHAW, RUSTY NANNYBERRY [Caprifoliaceae]

Viburnum rufidulum Raf., RUSTY BLACKHAW VIBURNUM, SOUTHERN BLACKHAW, RUSTY NANNYBERRY. Shrub, winter-deciduous, principal branches with opposite spur shoots bearing inflorescences and most leaves at ends, in range < 400 cm tall; shoots having distinctive, branched (stellate), short red to red-brown hairs on young, developing leaves and axes. Stems: cylindric, initially 2.5 mm in diameter, green with red hairs aging glabrate; periderm becoming dull brown bark. Leaves: opposite decussate, simple, petiolate often touching across node, without stipules; petiole half-cylindric, 7–16 mm long, red-pubescent mostly on flat upper side, on prophylls densely red-hairy on lower side, lacking glands along edges; blade obovate to broadly elliptic or ovate, < 50–90 × < 30−57 mm, somewhat leathery when mature, tapered at base, finely short-serrate on margins, rounded or obtuse to minutely notched at tip, pinnately veined with principal veins slightly sunken on upper surface and raised on lower surface, upper surface glabrous to glabrate and aging glossy, lower surface ± glossy, with red hairs persisting along midrib or other principal veins. Inflorescence: cyme, terminal, domelike to flat-topped with crowded flowers and buds, 30−60 mm across increasing in fruit, many-flowered, in range usually 3−4-branched at base and at first or second forks (pseudowhorled), dichasial above, bracteate, red-hairy on axes and bracts; bract subtending the lowest axis triangular, to 1.5 × 0.6 mm, red-hairy on back, bract or bractlet subtending upper axes deltate, < 0.7 mm long decreasing upward to minute awl-shaped; primary axes to 15 mm long increasing in fruit, secondary axes to 6 mm long, shorter upward; pedicel < 2 mm long, green, glabrous to glabrate, with 2 bracteoles at top subtending ovary, deltate but unequal, to 0.35 mm long. Flower: bisexual, radial, 6−6.5 mm across; mildly fragrant; calyx 5-lobed, ± 1 mm long; tube (hypanthium) dishlike; lobes roundish, 0.3−0.35 × 0.5−0.6 mm, whitish, sometimes with several minute teeth; corolla 5-lobed, broadly funnel-shaped, 3.5–4 mm long, white; tube 1 mm long; lobes roundish, 2.5−2.9 × 2.5−2.9 mm, overlapping at bases; stamens 5, fused 0.4−0.5 mm from base of corolla tube, alternate with corolla lobes (opposite sinuses); filaments equal, hooked in bud later ascending, ± 3 mm long, abruptly narrowed and tapered at tip, white, glabrous; anthers dorsifixed, dithecal, ± 1.2 mm long, light yellow, longitudinally dehiscent in bud; pollen light yellow; nectary forming disc on surface of style, nectar scanty at base of disc; pistil 1, green, glabrous; ovary inferior (appearing half-inferior), wedge-shaped, 1.5 × 1 mm, 2-chambered, each chamber with 1 ovule; style conic, ca. 1.2 mm; stigma indistinctly several-lobed, ca. 0.3 mm long. Fruit: drupe, with 1 stone, ± ellipsoid, in range 8−13.5 × < 8−9 mm, glaucous purple-red (especially upper side) and sometimes with a dark purple line on 1 side, having remnants of calyx at top appressed to brown base of style, with fleshy, purplish red pulp (mesocarp); stone indehiscent, flat and elliptic in outline compressed side-to-side, ca. 6.5−10.5 × 6.5 × 2 mm, tannish when immature later stained by pulp, extremely hard. A. C. Gibson